1. Field of the Invention
The present invention deals with filter assemblies. More particularly, the present invention deals with filter assemblies insertable in a bottle or reservoir. Most particularly, the present invention deals with a filter assembly which is placed in or connected to a reservoir of printing ink to filter the ink before it is carried to an ink module connected to a printing head.
2. Description of the Prior Art
Reservoir or bottle filters generally must meet two requirements. They must provide an effective and efficient method of filtration, and they must provide a way of measuring the level of fluid, such as ink, in a reservoir. In addition, they should be reliable and cost effective.
One such prior art filter is the Excel Series sold by Video Jet Systems International, Inc. of Wood Dale, Ill. This prior art filter has a cap having a grommet. Two thin flexible tubes are passed through the grommet into the reservoir. A larger flexible tube is passed over the smaller tubing, and held in place with a retaining means such as a rubber band. One of the tubes extends down slightly further then the other tube. This is the tube into which the fluid or ink is drawn.
To provide a filter, an external in-line filter is connected to the supply line by a pair of cable ties. The other tube serves as a level determining tube, and the movement of the fluid up and down in the tube provides a change in air pressure which can easily be measured by means well known in the art.
While this known filter is generally satisfactory, the fact that there must be a separate in-line filter outside the reservoir makes the filter somewhat bulky, and unwieldy. In addition, it is costly to manufacture. Thus, those skilled in the filter art continued to search for a satisfactory solution to the problem of providing a filter easily insertable into reservoir from which fluid was being drawn, and wherein the construction is compact and less expensive to manufacture.